Thanks for the bug report, not a lot you can do to fix it on your side besides starting a new campaign.

Hi guys FYI i had similar FTG campaign as empire - emperor stops dishing out missions, heroes other than vader, piet and veers are not buildable, and trigger planets for more advanced tech like deathstar/ endor arent happening anymore! Something has gone wrong with the scripted side, but all other generic units unlock and function correctly.